CARPENTERSVILLE – The District 300 board submitted a final contract offer to teachers Wednesday in negotiations hung up mainly on class sizes.

The “disappointed” board forwarded the offer to the union two days after the district’s teachers union, LEAD 300, officially declared an impasse in monthslong negotiations, said board member Joe Stevens, who is a lead district negotiator.

The offer would span three years and include salary increases, smaller class sizes, and cuts to retirement benefits and overload pay. Stevens estimated that ultimately its final offer would cost the district $6 million.